This is

is Scientific American 60 Second Science.

I'm Christopher Intagata.

The way we sample much of the world's oceans

to see what's living down there is pretty basic.

Ask fishermen. Or just stick a net down there and

examine what we catch. Neither method is ideal. Because you basically catch the fish

and kill them. Philip Francis Thompson, a biologist at the Natural History Museum of Denmark.

Another drawback he says is you can't do it everywhere.

If the bottom is too soft or too rocky or if there's a coral reef for example you don't want to use this

invasive method above sensitive habitat. So Thompson and his team

investigated an alternative that's been used in freshwater water with some success. They sample the diversity

and abundance of marine life using something called environmental DNA or e-dn-nay, basically genetic

material that fish leave behind.

So that is all sorts of bodily fluids that are expelled from a fish during its lifetime.

And beyond its lifetime too, like when one fish gets eaten and its remains get expelled in the

fecal matter of another.

Bingo, E-DNA.

Thompson and his colleagues sampled seawater at various steps off the southwest coast of Greenland, and then fished out the

E-DNA in those samples.

The researchers were able to identify 26 of the 28 fish families caught in the same area

in trawling trolling nets and at similar

...